[Tutor] != -1: versus == 1

[pedro]

Hi I have been trying to understand a python script and I keep coming 
across this kind of structure
that says "If it is not equal to negative one"

################################
for line in theLines:
    if line.find("Source Height") != -1:
#etc...
###################################

Is there some special reason for this. Why not just write "If it is 
equal to one"

#########################
for line in theLines:
    if line.find("Source Height") == 1:
#etc...
###################################
Pete