str.lstrip() removesall characters that appear in theset of characters you gave it. Since you gave it both0 and1 in that set, and the string consists ofonly zeros and ones, you removed the whole string.

In other words,str.lstrip() doesnot remove a prefix. It removes one character at a time, provided that character is named in the argument:

>>> '0123'.lstrip('0')'123'>>> '0123'.lstrip('10')'23'>>> '0123'.lstrip('20')'123'

Remove the firstlen(test) characters instead:

pro = pro[len(test):]

lstrip(chars) returns a copy of the string in which all chars have been stripped from the beginning of the string. so if you passtest that contain 1,0 it remove all the characters frompro (pro contain only 0,1) .

>>> pro = pro.lstrip('10')>>> pro''

instead you can Just use slicing :

>>> if pro.startswith(test):...    pro=pro[len(test):]... >>> pro'01111010010101001'

This is because lstrip removes all of the left characters from the set given so removes everything:

I think that you need:

pro = pro.startswith(test) and pro[len(test):] or pro

this will removetest from the start ofpro if it is there.

Just as extra.. This will also work:

>>> pro = "001001111010010101001">>> test = "0010">>> if pro.startswith(test):       pro = pro.partition(test)[-1]       print pro01111010010101001

• python