Find 'value' in a list of tokens and replace them with the 'key' of a dictionary. The dictionary can have multiple values per key. Example use: replacing multiple nick names with one common name.

replaceValuesWithKeys.py

s = ['c' ,'is', 'equal', 'to', 'b']
print(s)
# output >>  ['c', 'is', 'equal', 'to', 'b']
# dictionary of names:values
d = {'joe':['a', 'b'], 'tom':['c', 'd']}

# replace any values from the dict with the key value
for i in range(0, len(s)):
    for key,value in d.items():
        for v in value:
            s[i] = re.sub(r"\b%s\b" % v, key, s[i])
print(s)
# output >> ['tom', 'is', 'equal', 'to', 'joe']