In python, how do you check if a string has both uppercase and lowercase letters
<p>I've looked at the other post similar to my question, <a href="http://stackoverflow.com/questions/36380351/password-check-python-3">Password check- Python 3</a>, except my question involves checking if the password contains both uppercase and lower case questions. My code is the following, but when executed it fails to recognize that both lower and upper case letters are in the password, it only recognizes one type. How would I get it to recognize both types? Also is there an easier way to have the code check if all of those values occur without having to make functions for each individual step?</p>

<pre><code>def Get_Password():
    return input("Enter your desired password: ")

def Count_Digits(password):
    return sum(character.isdigit() for character in password)

def Valid_password_length(password):
    if len(password) &gt;= 10:
        return ('step1' == True)
    else:
        return ('step1' == False, print("Invalid password: too short"))

def Valid_password_characters(password):
    if password.isalnum():
        return ('step2' == True)
    else:
        return ('step2' == False, print("Invalid password: illegal character detected"))

def Valid_password_numdigit(password):
    if Count_Digits(password) &gt;= 2:
        return ('step3' == True)
    else:
        return ('step3' == False, print("Invalid password: Must have at least 2 digits"))

def Valid_password_lowercase(password):
    for i in (password):
        if i.islower() == True:
            return ('step4' == True)
        else:
            return ('step4' == False, print("Invalid password: No lowercase characters detected"))

def Valid_password_uppercase(password):
    for i in (password):
        if i.isupper() == True:
            return ('step5' == True)
        else:
            return ('step5' == False, print("Invalid password: No uppercase characters detected"))

def password_checker():
    password = Get_Password()
    Valid_password_length(password)
    Valid_password_characters(password)
    Valid_password_numdigit(password)
    Valid_password_lowercase(password)
    Valid_password_uppercase(password)

    if 'step1' and 'step2' and 'step3' and 'step4' and 'step5' == True:
        print("Congratulations! This password is valid")

password_checker()
</code></pre>

<pre><code>import sys

def Valid_password_mixed_case(password):
    letters = set(password)
    mixed = any(letter.islower() for letter in letters) and any(letter.isupper() for letter in letters)
    if not mixed:
        print("Invalid password: Mixed case characters not detected", file=sys.stderr)
    return mixed
</code></pre>

<p>A complete solution:</p>

<pre><code>import sys

def Get_Password():
    return input("Enter your desired password: ")

def Count_Digits(password):
    return sum(1 for character in password if character.isdigit())

def Valid_password_length(password):
    correct_length = len(password) &gt;= 10

    if not correct_length:
        print("Invalid password: too short", file=sys.stderr)

    return correct_length

def Valid_password_characters(password):
    correct_characters = password.isalnum()

    if not correct_characters:
        print("Invalid password: illegal character detected", file=sys.stderr)

    return correct_characters

def Valid_password_numdigit(password):
    sufficient_digits = Count_Digits(password) &gt;= 2

    if not sufficient_digits:
        print("Invalid password: Must have at least 2 digits", file=sys.stderr)

    return sufficient_digits

def Valid_password_mixed_case(password):
    letters = set(password)

    lower = any(letter.islower() for letter in letters)
    upper = any(letter.isupper() for letter in letters)

    if not upper:
        print("Invalid password: No uppercase characters detected", file=sys.stderr)

    if not lower:
        print("Invalid password: No lowercase characters detected", file=sys.stderr)

    return lower and upper

def password_checker():
    password = Get_Password()
    if Valid_password_length(password) and \
        Valid_password_characters(password) and \
        Valid_password_numdigit(password) and \
        Valid_password_mixed_case(password):

        print("Congratulations! This password is valid")

password_checker()
</code></pre>

python string