pub fn as_f64<'de, D>(deserializer: D) -> Result<f64, D::Error>where D: Deserializer<'de>,
De-serialize either a null, str, f64, u64, or i64 as a float value.
null
str
f64
u64
i64
Returns an error if a string is non-empty and not a valid numeric value.
The floating point (f64) value of a string or number.