method
    
    conv_arg
  conv_arg(arg, val = [])
  private
  Parses argument, converts and returns arg, block and result of conversion. Yields at semi-error condition instead of raising an exception.
  conv_arg(arg, val = [])
  private
  Parses argument, converts and returns arg, block and result of conversion. Yields at semi-error condition instead of raising an exception.