Flatten Array

flatten_array.py

def flatten_array( array, result ):
	""" if the array is empty then return [] """
	if not array:
		return []
	else:
		for a in array:
			""" if the current index is a number, take this number as part of the flattened result """
			if(isinstance(a,int)):
				result.append(a)
			else:
				""" if the current index is an array, recursively call the flatten method for this array"""
				flatten_array(a, result)	

def main():
	result = []
	flatten_array([[1,2, 3], [4]], result)
	print(result)

if __name__ == '__main__':
    main()

flatten_array_test.py

import unittest
from flatten_array import flatten_array
class FlattenArrayTests(unittest.TestCase):
	""" an empty array is naturally flattened"""
	def testEmptyArray(self):
		result = []
		flatten_array([], result)
		self.assertEqual(result, [])
	""" an array containing a single number is flattened by taking this number"""
	def testSingleNumberArray(self):
		result = []
		flatten_array([1], result)
		self.assertEqual(result, [1])
	""" an array within an array is flattened by taking the containing number """	
	def testArrayInArray(self):
		result = []
		flatten_array([[1]], result)
		self.assertEqual(result, [1])	    
def main():
	unittest.main()

if __name__ == '__main__':
	main()