python replace first time a char appears in a string code example

Example: python replace first occurrence in string

# string replace() function perfectly solves this problem:

# string.replace(s, old, new[, maxreplace])

# Return a copy of string s with all occurrences of substring old replaced 
# by new. If the optional argument maxreplace is given, the first maxreplace 
# occurrences are replaced.

>>> u'longlongTESTstringTEST'.replace('TEST', '?', 1)
u'longlong?stringTEST'