_getFileScopedHashMethodDefinition(id, contract){
    const hash = web3Utils.keccak256(id).slice(2,10);
    const method = this._getDefaultMethodIdentifier(id);
    const abi = this._getAbiEncodeStatementVar(hash);

    return (this.viaIR)
      ? `\nfunction ${method}(bytes8 c__${hash}) pure { ${abi} }\n`
      : `\nfunction ${method}(bytes8 c__${hash}) pure {}\n`;
  }
Generates an instrumentation fn definition for file scoped methods.
Declared once per file. (Has no visibility modifier)
@param  {String} id
@return {String}