(Go series) Assign | Go topic month to a map with a value of nil

Original text: yourbasic.org/golang/gotc…

Why did this program cause Panic?

var m map[string]float64
m["pi"] = 3.1416
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panic: assignment to entry in nil map
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answer

Before adding elements to a map, you need to initialize the map using either the make function or a map literal.