class Exception_(Exception):
    """Base class for exceptions in this module."""
    pass

class InvalidRepresentationTypeError(Exception_):
    pass

class InvalidCombinationMethodError(Exception_):
    pass

class InvalidSpecError(Exception_):
    pass

class InvalidSampleError(Exception_):
    pass

class CitationNotImplementedError(Exception_):
    pass

class ArgumentRequiredError(Exception_):
    pass