L20Q3_Rotate.py

# Write a procedure, rotate which takes as its input a string of lower case
# letters, a-z, and spaces, and an integer n, and returns the string constructed
# by shifting each of the letters n steps, and leaving the spaces unchanged.
# Note that 'a' follows 'z'. You can use an additional procedure if you
# choose to as long as rotate returns the correct string.
# Note that n can be positive, negative or zero.

from L20Q2_ShiftNLetters import shift_n_letters

def rotate(phrase,n):
    phraseout=""
    for i in phrase:
        if ord(i) == 32:
            phraseout += " "
        else:
            phraseout += shift_n_letters(i,n)
    return phraseout

print rotate ('sarah', 13)
#>>> 'fnenu'
print rotate('fnenu',13)
#>>> 'sarah'
print rotate('dave',5)
#>>>'ifaj'
print rotate('ifaj',-5)
#>>>'dave'
print rotate(("zw pfli tfuv nfibj tfiivtkcp pfl jyflcu "
                "sv rscv kf ivru kyzj"),-17)
#>>> ???