import re

# This function comes from our tutorial PDF.
def matches(regexp, string):
    return re.search(r"\A(?:" + regexp + r")\Z", string) != None

# Let's agree that a word is said to be mis-capitalized if it consists of two or 
# more letters and any letter after the first one is upper-case. We assume that 
# only alphabetical characters appear in words. This Python regular expression 
# is supposed to match exactly mis-capitalized words.
miscapitalized = r""

# An e-mail address such as 'superSnake@carleton.edu' consists of a local part, 
# 'superSnake', and a hostname, 'carleton.edu'. The local part is a string made 
# of one or more characters from this set: upper- and lower-case English 
# letters, the digits '0' through '9', the characters '!', '#', '$', '%', '&', 
# ''', '*', '+', '-', '/', '=', '?', '^', '_', '`', '{', '|', '}', '~', and the 
# period '.'. The hostname is a string made of one or more characters from this 
# set: lower-case English letters, the digits '0' through '9', the period '.', 
# and the hyphen '-'. Neither the local part nor the hostname can begin or end 
# in a period. The local part and the hostname are separated by a single '@'. 
# (There are a few more rules to real e-mail addresses, but this is good enough 
# for our purposes.) Here are four relevant character classes.
localwo = r"[\w!#\$%&'\*\+\-/=\?\^_`\{\|\}~]"
localw = r"[\w!#\$%&'\*\+\-/=\?\^_`\{\|\}~\.]"
hostwo = r"[a-z0-9-]"
hostw = r"[a-z0-9\-\.]"

# Here is a regular expression that matches e-mail addresses as just described.
email = r""

# I like to write my dates in the format yyyy/mm/dd, but sometimes I 
# accidentally write mm/dd/yyyy because that's how I was raised. The following 
# Python function takes a string as input, uses a regular expression to fix 
# all dates in the string to my liking, and returns the fixed string. All 
# years are four-digit --- I'm Y2K-compliant --- but months and days can be 
# one- or two-digit. (Hint: You need to use substitutions and multiple groups. 
# My solution is one line of code.)
def fixDates(string):
    return ""

# Runs tests. (Feel free to add more test cases.)
def main():
    print("First test: mis-capitalized words...")
    student = re.findall(miscapitalized, "This is okay tHis IS nOT.")
    jrd = ["tHis", "IS", "nOT"]
    print(student == jrd)
    print("Second test: valid e-mail addresses...")
    print(matches(email, "superSnake@carleton.edu"))
    print(matches(email, "-babatope-44017@cheese"))
    print("Third test: invalid e-mail addresses...")
    print(matches(email, "josh@.edu"))
    print(matches(email, "nerd@stolaf@edu"))
    print("Fourth test: fixing dates...")
    print(fixDates("Why did I pick the dates 4/17/2009, 11/9/2007?"))

# If the user imported this file as a module into another program, then don't 
# run main(). If the user ran this file directly, then do run main().
if __name__ == "__main__":
    main()