I get request from html post form on python socket, but I cant get value of field, How can I get parameter value from the form that send like request?

This is the string response but I cant get value of field in the string, ej, fecha_graduacion_bachiller value or fecha_nacimiento value

POST /formulario HTTP/1.1
Host: localhost:8791
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: http://localhost:8791/
Content-Type: application/x-www-form-urlencoded
Content-Length: 191
Connection: keep-alive
Upgrade-Insecure-Requests: 1

nombre1=4&nombre2=43334&apellido1=4&apellido2=43433&codigo_identificacion=4&identificacion=4&fecha_nacimiento=2019-10-01&codigo_pais_nacimiento=4&sexo=-1&fecha_graduacion_bachiller=2019-09-30