dropCovFromFormla
adds drops some covariates from a
formula; covs should be a list of variable names
Examples
formla <- y ~ x + w + z
dropCovFromFormla(list("w", "z"), formla)
#> y ~ x
#> <environment: 0x55c7730a8df0>
dropCovFromFormla("z", formla)
#> y ~ x + w
#> <environment: 0x55c773107cb8>