def whereis(s1,s2):
    '''whereis(str, str) - > int/boolean
    
    Returns the index number of the first occurence of the single letter 
    string s2 in the string s1. Returns False if the parameters given are not 
    strings and if s2 is not a single letter in length.'''

    if ( type(s1) != str ) or ( type(s2) != str ):
        return False
    
    if len(s2) != 1:
        return False
    
    return s1.find(s2)


def reverse(original_list):
    '''reverse(list) - > list/boolean
    
    Given a list, returns a new list in which the elements of the original
    list have been reversed. Returns False if the parameter given is not a list. 
    '''
    
    if ( type(original_list) != list ) :
        return False

    new_list = []
    for element in original_list:
        new_list.insert(0,element)
    
    return new_list