'Returns available converters by source type'

def get_converters_by_datatype(self, ext):

    converters = odict()
    source_datatype = type(self.get_datatype_by_extension(ext))
    for (ext2, converters_dict) in self.datatype_converters.items():
        converter_datatype = type(self.get_datatype_by_extension(ext2))
        if issubclass(source_datatype, converter_datatype):
            converters.update(converters_dict)
    if (ext in self.datatype_converters.keys()):
        converters.update(self.datatype_converters[ext])
    return converters
