pub fn as_i64<'de, D>(deserializer: D) -> Result<i64, D::Error>where D: Deserializer<'de>,
De-serialize either a null, str, i64, f64, or u64 as a signed value.
null
str
i64
f64
u64
Returns an error if a string is non-empty and not a valid numeric value, or if the unsigned value u64 overflows when converted to i64.
The signed (i64) value of a string or number.