import re
# w is equivalent to [a-zA-Z0-9_].
p = re.compile('w')
print(p.findall("He said * in some_lang."))
# w+ matches to group of alphanumeric character.
p = re.compile('w+')
print(p.findall("I went to him at 9 A.M., he
said *** in some_language."))
# W matches to non alphanumeric characters.
p = re.compile('W')
print(p.findall("he said *** in some_language."))