def FunctionName(headings):
    for c in headings:
        exec('global %s' % c)
<Other code...>

import modulename
headings = ['test1','test2','test3']
modulename.FunctionName(headings)
print(dir(modulename))
print(modulename.test1)

['FunctionName',<Other function but no variables>]
Traceback (most recent call last):
File "<path>main_program.py", line 6,
in <module>
print(modulename.test1)
AttributeError: module 'modulename' has no attribute 'nice'

global <Var name>