param_letters with no numbers after parameter do not work

[VisComKreiser]

Hey,

i've got gcode lines like:

• T1 R
• M1013 R

and if there is no number after the "R", i get the exception GCodeWordStrError : word 'R' value invalid

I have added the classes:

class GCodeParkReturn(GCode):
    """M1013: park/return"""
    word_key = Word('M', 1013)
    word_letter = 'M'
    param_letters = set('R')

class GCodeSwitchExtruder(GCode):
    """T1: switch extruder"""
    word_key = Word('T', 1)
    word_letter = 'T'
    param_letters = set('R')

E.g. T1 R123 does work without an issue with the added "123" after the "R"
Is there an option to allow zero parameter values? Maybe I have just missed it.

I'm testing it using text2gcodes('T1 R')

Thanks.

[VisComKreiser]

can it be that this is only possible in RepRap GCode?