Netsnmp_raw.PduSourcesnmp_pdu_create pdu_type creates a PDU of the specified type, the associated memory is not part of the OCaml heap.
The PDU will be freed when the OCaml memory is garbage collected
snmp_add_null_var adds an oid to a pdu with a null value. Used to build a request PDU
snmp_add_variable adds an oid and value to a pdu Used to build a request PDU