_getFileScopeTrueMethodDefinition(id){
    const hash = web3Utils.keccak256(id).slice(2,10);
    const method = this._getTrueMethodIdentifier(id);
    const abi = this._getAbiEncodeStatementVar(hash);

    return (this.viaIR)
      ? `function ${method}(bytes8 c__${hash}) pure returns (bool){ ${abi} return true; }\n`
      : `function ${method}(bytes8 c__${hash}) pure returns (bool){ return true; }\n`;
  }
Generates a solidity statement injection defining a method
*which returns boolean true* to pass instrumentation hash to.
Declared once per file. (Has no visibility modifier)
@param  {String} fileName
@return {String}          ex: bytes32[1] memory _sc_82e0891