function for extracting data from lists

[Paulman]

OK thanks, then I did the following code:

def main(list_1):
    return main

list_1 = [
    {'name': 'Jerome', 'weight': 3.38, 'wingspan': 49.96, 'length': 19.75},
    {'name': 'Ibraheem', 'weight': 3.08, 'wingspan': 50.59, 'length': 20.6},
    {'name': 'Tiana', 'weight': 0.81, 'wingspan': 47.86, 'length': 17.94},
    {'name': 'Lucas', 'weight': 3.33, 'wingspan': 48.27, 'length': 18.77},
    {'name': 'Rickie', 'weight': 4.4, 'wingspan': 51.0, 'length': 20.34}
]

def get_data(data,key):
    y=[]
    for x in data:
        return y=x[key]
data = list_1
get_data(list_1,'length')
output = get_data(data,key)
print(output, end=" ")

I'm getting a syntax error in "return y=x[key]", why is that?