synth_data: Tidy Data for Synthetic Control
In kbrevoort/tidysynth: What the package does (short line)

Tidy Data for Synthetic Control

1	synth_data(formula, data, i_var, t_var, treatment)

`data`	A data.frame
`i_var`	Name of the variable denoting individual subjects
`t_var`	Name of the variable reflecting time
`treatment`	An NSE statement designating which i are among the treatment (not control) observations
`y`	Names of variable(s)
`z`	A list of control variables. Each element of the list should be a vector with 2-3 elements. The first element is the definition of the variable using NSE. The second element will be the filter argument and the third (optional) will be the name for the element.