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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 build_schema( source: Union[str, Source], assume_valid=False, assume_valid_sdl=False, no_location=False, experimental_fragment_variables=False, ) -> GraphQLSchema: """Build a GraphQLSchema directly from a source document."""

    return build_ast_schema(
        parse(
            source,
            no_location=no_location,
            experimental_fragment_variables=experimental_fragment_variables,
        ),
        assume_valid=assume_valid,
        assume_valid_sdl=assume_valid_sdl,
    )