string_to_test = 'She sells seashells on the seashore'
# let's say you want to find all words containing 'sea' in it
import re
# considering you want a case-insensitive search
regex_obj = re.compile('sea\w*',flags=re.I)
# the re.I signifies case-insensitive search
# the \w signifies any letters, numbers or underscore,
# so in this case, it means any letter after the string 'sea'
# the * signifies one or more occurrences, thus taken together,
# 'sea\w*' signifies one or more instances of any letter,
# number or underscore
list_of_matches = regex_obj.findall(string = string_to_test)
# returns ['seashells','seashore']