def flatten(x):
"""flatten(sequence) -> list"""
result = []
for el in x:
# alternatively:
# if isinstance(el, (list, tuple)):
if type(el)==list or type(el)==tuple:
result.extend(flatten(el))
else:
result.append(el)
return result
print(flatten([(1, 2), "Python", ["a", [1,7]], 1, 1.3]))