You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: map_claims.go
    path of file: ./repos/jwt
    
    the code of the file until where you have to start completion: package jwt

import (
	"encoding/json"
	"fmt"
)

// MapClaims is a claims type that uses the map[string]interface{} f
    
func (m MapClaims) parseNumericDate(key string) (*NumericDate, error) {
	v, ok := m[key]
	if !ok {
		return nil, nil
	}

	switch exp := v.(type) {
	case float64:
		if exp == 0 {
			return nil, nil
		}

		return newNumericDateFromSeconds(exp), nil
	case json.Number:
		v, _ := exp.Float64()

		return newNumericDateFromSeconds(v), nil
	}

	return nil, newError(fmt.Sprintf("%s is invalid", key), ErrInvalidType)
}