#run foogoo
foo()
go0()
x = foo()
x
x=goo()
x
print x
def f3():
return 3
print "done"
f3()
def f4():
print "done"
return 3
f3()

#Back to slides.
def f(x):
x= 5
print x

x=9
x
f(x)
x


true
#note that true is not a keyword, but you still shouldn't use it for anything.
True
type(True)
not True
True and True
True and False
False or True
x=True
not x
x and x#back to slides
#relational operators
5>3
3>5
4>2.0
4==4.0
#Note that it's still a good idea to make the types match in a relational
expression, because sometimes values aren't what you'd expect.
x=5
x!=5.0
x>=5 #back to slides.
#Bad style
5+7<4*3 or 1-2 >2-4 and 15==4
#Better to use parentheses if you aren't sure.
((5+7)<(4*3)) or ((1-2) >(2-4)) and (15==4) 
#weirdness starts
x=4
x and True
#This is because python considers any non-0 numbers to be true.
x=-2
x and True
x=x +True
x
x=x+False
x
#True is represented as 1, False as 0.
#Short-circuit evaluation weirdness.
x=4.0 or True
x= True or 4.0
#Really bad style
5+7<4*3 or 1-2 >2-4 and 15
#Back to slides.

x = True
x
print x