def sum_array(array):

    ''' Return sum of all items in array'''

    arr = sum(array)
    return arr

def fibonacci(n): 
   
    '''Return nth term in fibonacci sequence'''
    
    if n <= 1:
        return n
    else: 
        return fibonacci(n-1)+fibonacci(n-2)

def factorial(n):

    '''Return n!'''
    if n <= 1:
        return 1
    else:
        return n * factorial(n-1)

def reverse(word):

    '''Return word in reverse'''
    return word[::-1]
