code: def _python_instance_to_nexml_meta_datatype(v):
      
      if isinstance(v, bool):
          return 'xsd:boolean'
      if is_int_type(v):
          return 'xsd:int'
      if isinstance(v, float):
          return 'xsd:float'
      return 'xsd:string'
docs: Returns 'xsd:string' or a more specific type for a <meta datatype="XYZ"...
      syntax using introspection.