[1b0b3ca] | 1 | # This program is public domain |
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| 2 | """ |
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| 3 | File extension registry. |
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| 4 | |
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| 5 | This provides routines for opening files based on extension, |
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| 6 | and registers the built-in file extensions. |
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| 7 | """ |
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| 8 | import imp,os,sys |
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| 9 | import logging |
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| 10 | import os.path |
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| 11 | |
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| 12 | |
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| 13 | def _findReaders(dir): |
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| 14 | # List of plugin objects |
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| 15 | plugins = [] |
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| 16 | # Go through files in plug-in directory |
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| 17 | try: |
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| 18 | |
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| 19 | list = os.listdir(dir) |
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| 20 | for item in list: |
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| 21 | |
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| 22 | toks = os.path.splitext(os.path.basename(item)) |
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| 23 | if toks[1]=='.py' and not toks[0]=='__init__': |
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| 24 | name = toks[0] |
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| 25 | path = [os.path.abspath(dir)] |
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| 26 | file = None |
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| 27 | |
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| 28 | try: |
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| 29 | (file, path, info) = imp.find_module(name, path) |
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| 30 | module = imp.load_module( name, file, item, info ) |
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| 31 | if hasattr(module, "Reader"): |
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| 32 | try: |
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| 33 | plugins.append(module.Reader()) |
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| 34 | except: |
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| 35 | log("Error accessing Reader in %s\n %s" % (name, sys.exc_value)) |
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| 36 | except : |
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| 37 | log("Error importing %s\n %s" % (name, sys.exc_value)) |
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| 38 | finally: |
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| 39 | if not file==None: |
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| 40 | file.close() |
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| 41 | except: |
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| 42 | # Should raise and catch at a higher level and display error on status bar |
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| 43 | pass |
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| 44 | return plugins |
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| 45 | class Loader(object): |
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| 46 | """ |
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| 47 | Associate a file loader with an extension. |
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| 48 | |
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| 49 | Note that there may be multiple readers for the same extension. |
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| 50 | |
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| 51 | Example: |
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| 52 | |
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| 53 | registry = Loader() |
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| 54 | |
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| 55 | # Add an association by setting an element |
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| 56 | registry['.zip'] = unzip |
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| 57 | |
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| 58 | # Multiple extensions for one loader |
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| 59 | registry['.tgz'] = untar |
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| 60 | registry['.tar.gz'] = untar |
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| 61 | |
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| 62 | # Multiple readers for one extension |
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| 63 | registry['.cx'] = cx1 |
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| 64 | registry['.cx'] = cx2 |
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| 65 | registry['.cx'] = cx3 |
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| 66 | |
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| 67 | # Can also register a format name for explicit control from caller |
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| 68 | registry['cx3'] = cx3 |
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| 69 | |
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| 70 | # Retrieve readers for a file name |
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| 71 | registry.lookup('hello.cx') -> [cx3,cx2,cx1] |
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| 72 | |
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| 73 | # Run loader on a filename |
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| 74 | registry.load('hello.cx') -> |
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| 75 | try: |
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| 76 | return cx3('hello.cx') |
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| 77 | except: |
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| 78 | try: |
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| 79 | return cx2('hello.cx') |
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| 80 | except: |
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| 81 | return cx1('hello.cx') |
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| 82 | |
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| 83 | # Load in a specific format ignoring extension |
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| 84 | registry.load('hello.cx',format='cx3') -> |
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| 85 | return cx3('hello.cx') |
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| 86 | """ |
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| 87 | def __init__(self): |
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| 88 | self.readers = {} |
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| 89 | self.reading=None |
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| 90 | self.dir='plugins' |
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| 91 | self.__setitem__() |
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| 92 | |
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| 93 | def set_pluginDir (self,path): |
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| 94 | """ specify the name of folder containing pluging""" |
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| 95 | if not os.path.isdir(path): |
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| 96 | os.mkdir(path) |
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| 97 | self.dir=path |
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| 98 | def __setitem__(self, ext=None, reader=None): |
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| 99 | if reader==None: |
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| 100 | plugReader=None |
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| 101 | if os.path.isdir(self.dir): |
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| 102 | plugReader=_findReaders(self.dir)# import all module in plugins |
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| 103 | elif os.path.isdir('../'+self.dir): |
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| 104 | plugReader=_findReaders('../'+self.dir) |
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| 105 | if plugReader !=None: |
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| 106 | for preader in plugReader:# for each modules takes list of extensions |
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| 107 | #print preader.ext |
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| 108 | for item in preader.ext: |
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| 109 | ext=item |
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| 110 | if ext not in self.readers:#assign extension with its reader |
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| 111 | self.readers[ext] = [] |
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| 112 | self.readers[ext].insert(0,preader) |
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| 113 | else: |
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| 114 | if ext not in self.readers: |
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| 115 | self.readers[ext] = [] |
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| 116 | self.readers[ext].insert(0,reader) |
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| 117 | |
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| 118 | |
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| 119 | def __getitem__(self, ext): |
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| 120 | return self.readers[ext] |
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| 121 | |
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| 122 | |
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| 123 | |
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| 124 | def __contains__(self, ext): |
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| 125 | return ext in self.readers |
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| 126 | |
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| 127 | |
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| 128 | def formats(self, name=True, ext=False): |
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| 129 | """ |
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| 130 | Return a list of the registered formats. If name=True then |
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| 131 | named formats are returned. If ext=True then extensions |
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| 132 | are returned. |
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| 133 | """ |
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| 134 | names = [a for a in self.readers.keys() if not a.startswith('.')] |
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| 135 | exts = [a for a in self.readers.keys() if a.startswith('.')] |
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| 136 | names.sort() |
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| 137 | exts.sort() |
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| 138 | ret = [] |
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| 139 | if name: ret += names |
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| 140 | if ext: ret += exts |
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| 141 | return ret |
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| 142 | |
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| 143 | def lookup(self, path): |
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| 144 | """ |
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| 145 | Return the reader associated with the file type of path. |
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| 146 | """ |
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| 147 | file = os.path.basename(path) |
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| 148 | idx = file.find('.') |
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| 149 | ext = file[idx:] if idx >= 0 else '' |
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| 150 | try: |
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| 151 | return self.readers[ext] |
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| 152 | except: |
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| 153 | #raise ValueError, "Unknown file type '%s'"%ext |
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| 154 | print "Unknown file type '%s'"%ext |
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| 155 | |
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| 156 | |
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| 157 | def getAcTReader(self,path): |
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| 158 | """ return Reader actually reading""" |
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| 159 | return self.reading |
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| 160 | |
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| 161 | def load(self, path, format=None): |
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| 162 | """ |
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| 163 | Call the loader for the file type of path. |
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| 164 | |
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| 165 | Raises ValueError if no loader is available. |
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| 166 | May raise a loader-defined exception if loader fails. |
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| 167 | """ |
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| 168 | if format is None: |
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| 169 | readers = self.lookup(path) |
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| 170 | else: |
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| 171 | readers = self.readers[format] |
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| 172 | if readers!=None: |
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| 173 | for fn in readers: |
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| 174 | try: |
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| 175 | value=fn.read(path) |
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| 176 | self.reading= fn.__class__ |
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| 177 | return value |
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| 178 | except ValueError,msg: |
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| 179 | print str(msg) |
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| 180 | if __name__=="__main__": |
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| 181 | l=Loader() |
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| 182 | print "look up",l.lookup('angles_flat.png') |
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| 183 | print l.__getitem__('.tiff') |
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| 184 | print l.__getitem__('jpeg') |
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| 185 | print l.__contains__('.tiff') |
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| 186 | |
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