Just change the function definition to:
def load():
global var # this line has been added to the original code
var = something()
Global variables are read-only from sibling methods. More accurately unless a variable is specified as global, Python consider it as local, but a read access to a local variable name will reach module-level scope if the name is not present in local scope.
See also use of “global” keyword in python and the doc for more details about the global statement