pivot_rate_module: The server function for a pivot table module
In ablack3/shinyPivot:

Description Usage Arguments Value Examples

This function should be passed to callModule. See example.

1 2	pivot_rate_module(input, output, session, ns_id, numer_df, denom_df, pivot_vars, record_limit = 1e+06, show_filter_text = T)

`input`	A standard argument used by shiny when creating the module.
`output`	A standard argument used by shiny when creating the module.
`session`	A standard argument used by shiny when creating the module.
`ns_id`	The module namespace id as a string. Must match a namespace id of the corresponding UI module element.
`pivot_vars`	A table constructed using the get_pivot_vars function.
`record_limit`	The maximum number of rows to bring into R to display. This is a saftely measure. You probably don't want to bring 100 million rows of data into R from a database. Defaults to 1 million.
`df`	A local dataframe/tibble or tbl_dbi database connection object.

The server function needed for a pivot table module.

 # note that the namespace id must
server <- function(input, output, session){
   callModule(pivot_module, id = "id1", ns_id = "id1", df = df1, pivot_vars = pivot_vars1, record_limit = 20)
}