Function lookup_parameter_contract 

pub fn lookup_parameter_contract(
    source_name: &str,
    source_variant: &BTreeMap<String, String>,
    target_name: &str,
    target_variant: &BTreeMap<String, String>,
) -> Result<Option<ReductionParameterContract>, ParameterContractError>

Look up the explicit parameter contract for an exact direct reduction entry.