code: function encodeSignature(method) {
    const signature = `${method.name}(${utils.getKeys(method.inputs, 'type').join(',')})`;
    const signatureEncoded = `0x${(new Buffer(utils.keccak256(signature), 'hex')).slice(0, 4).toString('hex')}`;
  
    return signatureEncoded;
  }
docs: create an encoded method signature from an ABI object