Best way to check wether a square is "next to" another square.

is-it-next-to.py

# Returns `True` if the square at `a` is in one of the
# **eight surrounding squares** of `b`; `False` otherwise.

def nextTo(a, b):
  x = a[0] - b[0]
  y = a[1] - b[1]

  d = x*x + y*y
  return 0 < d < 3

usage.py

a = [4, -7]
b = [3, -8]

if nextTo(a, b):
  print "Yes, they're next!"
else:
  print "No, sorry."