Call this function as an add-in to insert ` %in% `

at the cursor position.

`rs_insert_infix_in()`

Operator %in%.

Other 'Insert at cursor position' add-ins: `insert_magrittr_operators`

,
`rs_insert_infix_R`

,
`rs_insert_infix_not_in`

,
`rs_insert_matrix_multiplication`