deftrim(s):

    n=0

while n<len(s):

if s[n:n+1] == ' ':

            s1=s[n+1:]

            n=n+1

else:

break

    n=len(s1)

while n>0:

if s1[n-1:n] == ' ':

            s2=s1[:n-1]

            n=n-1

else:

break

return s2