python - UnboundLocalError when assigning function result to variable named the same as the function

Question

Why am I getting

UnboundLocalError: local variable 'heatmap' referenced before assignment

in the below script on the line heatmap = heatmap()?

def heatmap():
    heatmap = "123"
    return heatmap

def run():
   heatmap = heatmap()
   return heatmap

print(run())

Answer 1

Because you are using same names for functions and for local variables. Should not do this.

This line:

heatmap = heatmap()

first declares new variable heatmap, thus shadowing function, and then tries to call heatmap() to initialize it. But at this moment there is already no such function, because from now it is a local variable