how to access all element of array in another struct?

[UndefinedIdentifier]

I have a script which get instruction place on EIP

ins = pluginsdk.x64dbg.DISASM_INSTR()
pluginsdk.x64dbg.DbgDisasmAt(Register.EIP, ins)

ins has an array field name arg,and arg has 3 element.
I can only access first element of arg.
there is no idea how to aceess other element of arg

typedef struct
{
DISASM_ARGTYPE type; //normal/memory
SEGMENTREG segment;
char mnemonic[64];
duint constant; //constant in the instruction (imm/disp)
duint value; //equal to constant or equal to the register value
duint memvalue; //memsize:[value]
} DISASM_ARG;

typedef struct
{
char instruction[64];
DISASM_INSTRTYPE type;
int argcount;
int instr_size;
DISASM_ARG arg[3];
} DISASM_INSTR;