import re

​

text = "The rain in Spain falls mainly on the plain"

​

#Find and return words that contains the phrase "ain":

​

pattern = """

[A-Za-z]* #starts with any letter

ain+      #contains 'ain'

[a-z]*    #followed by any small letter

"""

​

print(re.findall(pattern, text, re.VERBOSE))

​

#The example would return nothing without the re.VERBOSE flag

print(re.findall(pattern, text))

​

​

#Same result with the shorthand re.X flag:

print(re.findall(pattern, text, re.X))

​