Cannot call main function but I don't know why

[eml]

I don't know why I get an error with this
It says main is not defined

while True:
    main ()

def main(): 
    MainMenu = input("""Please select a function
    [1] Read Data
    [2] Write data
    [3] Filter data
    [4] Quit database
    """)

[j.crater]

Put main function definition before the while loop.

[eml]

Put main function definition before the while loop.

THANNNNK YOUUUUU