code: def _writecheck(self, zinfo):
          
          if zinfo.filename in self.NameToInfo:
              if self.debug:      # Warning for duplicate names
                  print "Duplicate name:", zinfo.filename
          if self.mode not in ("w", "a"):
              raise RuntimeError, 'write() requires mode "w" or "a"'
          if not self.fp:
              raise RuntimeError, \
                    "Attempt to write ZIP archive that was already closed"
          if zinfo.compress_type == ZIP_DEFLATED and not zlib:
              raise RuntimeError, \
                    "Compression requires the (missing) zlib module"
          if zinfo.compress_type not in (ZIP_STORED, ZIP_DEFLATED):
              raise RuntimeError, \
                    "That compression method is not supported"
          if zinfo.file_size > ZIP64_LIMIT:
              if not self._allowZip64:
                  raise LargeZipFile("Filesize would require ZIP64 extensions")
          if zinfo.header_offset > ZIP64_LIMIT:
              if not self._allowZip64:
                  raise LargeZipFile("Zipfile size would require ZIP64 extensions")
docs: Check for errors before writing a file to the archive.