code: function(message, privateKey, cb = null)
  	{
          var result
          try {
              result = secp256k1.sign(ethUtils.sha3(message), privateKey)
          }
          catch (err){
              result = err
          }
          if(isFunction(cb)){
              if(result instanceof Error){
                  return cb(result)
              } else {
                  return cb(null, result)
              }
          }
          else {
              return result
          }
  	}
docs: sign a message hashed with sha3 (256 bit) using the ethereum private key
  @param  {String} message    The message to sign
  @param  {Buffer} privateKey The ethereum private key used to sign the message
  @return {Object}            Signature object with the keys signature and recovery