Concatenated / Multipart

[masday86]

hello i'm read https://www.openmarket.com/docs/Content/apis/v3smpp/smpp-multipart-messages.htm
so need to change udhheader from

    UDHHeader := make([]byte, 7)
UDHHeader[0] = 0x06              // length of user data header
UDHHeader[1] = 0x08              // information element identifier, CSMS 16 bit reference number
UDHHeader[2] = 0x04              // length of remaining header
UDHHeader[3] = uint8(rn >> 8)    // most significant byte of the reference number
UDHHeader[4] = uint8(rn)         // least significant byte of the reference number
UDHHeader[5] = uint8(countParts) // total number of message parts

to
UDHHeader := make([]byte, 7)
UDHHeader[0] = 0x05 // Length of the rest of the UDH. This is "5" bytes.
UDHHeader[1] = 0x00 //Indicates it is a multipart message.
UDHHeader[2] = 0x03 // Length of the subheader; e.g., the rest of the UDH. This is "3" bytes.
UDHHeader[3] = uint8(rn >> 8) // Total number of parts in the multipart message.
UDHHeader[4] = uint8(countParts) // total number of message parts

can you help how i can do it?