def trim(str):    len1 = len(str) - 1    i = 0    t = len1    firstFlat = True    endFlat = True    while len1>=i:        if firstFlat and ' '== str[i:i+1]:            i = i+1        if endFlat and ' '==str[len1:len1+1]:            t = t -1        len1 = len1 -1    return str[i:t+1]