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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def RegisterParser(cls, parser_class):
 """Registers a parser class. The parser classes are identified based on their lower case name. Args: parser_class (type):
 parser class (subclass of BaseParser). Raises: KeyError: if parser class is already set for the corresponding name. """

    parser_name = parser_class.NAME.lower()
    if parser_name in cls._parser_classes:
      raise KeyError('Parser class already set for name: {0:s}.'.format(
          parser_class.NAME))

    cls._parser_classes[parser_name] = parser_class