Examples of handy functions including Factorial, Fibonacci and palindrome finding functions using both recursion and loops.

main.py

def get_factorial_recursively(i):
    f = 1
    if i > 1:
        f = f * i * get_factorial_recursively(i - 1)
    return f

def get_factorial_iteratively(i):
    f = 1
    for j in range(2, i + 1):
        f = f * j
    return f

def get_factorial_string_iteratively(i):
    s = "1"
    for j in range(2, i + 1):
        s = s + ", " + str(j)
    return s

def get_fibonacci_series_term_recursively(i):
    f = i
    if i > 1:
        f = get_fibonacci_series_term_recursively(i - 1) + get_fibonacci_series_term_recursively(i - 2)
    return f

def get_fibonacci_series_term_iteratively(i):
    f, f1, f2 = 0, 0, 1
    for j in range(0, i):
        f = f1 + f2
        f2 = f1
        f1 = f
    return f

def get_fibonacci_series_string_iteratively(i):
    s = "0"
    f, f1, f2 = 0, 0, 1
    for j in range(0, i):
        f = f1 + f2
        f2 = f1
        f1 = f
        s = s + ", " + str(f)
    return s

def reverse(str):
   return str[::-1]

def palindrome_recursively(str):
    r = True
    i = len(str)
    if i > 1:
        if str[:1] == str[i - 1:]:
            r = palindrome_recursively(str[1:i - 1])
        else:
            r = False
    return r

def palindrome_iteratively(str):
    r = True
    i = len(str)
    if i > 1:
        half = i // 2
        for j in range(0, half):
            if str[j:j + 1] != str[i - j - 1:i - j]:
                r = False
    return r

if __name__ == "__main__":
    answer = get_factorial_recursively(6)
    assert(answer == 720)

    answer = get_factorial_iteratively(6)
    assert(answer == 720)

    answer = get_fibonacci_series_term_recursively(7)
    assert(answer == 13)

    answer = get_fibonacci_series_term_iteratively(7)
    assert(answer == 13)

    answer = get_fibonacci_series_string_iteratively(4)
    assert(answer == "0, 1, 1, 2, 3")

    hw = "Hello World!"
    answer = reverse(hw)
    assert(answer == "!dlroW olleH")

    assert(palindrome_recursively("helloolleh") != False)
    assert(palindrome_recursively("helolleh") == False)

    assert(palindrome_iteratively("helloolleh") != False)
    assert(palindrome_iteratively("helolleh") == False)

    input("Press <Enter>")