lib/files/js.js
function _sigName(src) {
  if (!_.isFunction(src)) return ''
  let ret = _.trim(_.replace(src.toString(), 'function', ''))
  ret = ret.substr(0, ret.indexOf('('))
  return ret || ''
}
function _sigName(src) {
  if (!_.isFunction(src)) return ''
  let ret = _.trim(_.replace(src.toString(), 'function', ''))
  ret = ret.substr(0, ret.indexOf('('))
  return ret || ''
}
returns function signature name