text = ‘xxxx’
>>> d = {‘xxx’ : ‘3’,’xx’ : ‘2’}
>>> for k in sorted(d, key=len, reverse=True): # Through keys sorted by length
text = text.replace(k, d[k])
>>> text'3x'

text = ‘xxxx’
>>> d = {‘xxx’ : ‘3’,’xx’ : ‘2’}
>>> for k in sorted(d, key=len, reverse=True): # Through keys sorted by length
text = text.replace(k, d[k])
>>> text'3x'