get_model_matrix: Extract or remake model matrix from model
In lmerTest: Tests in Linear Mixed Effects Models

Extract or remake model matrix from model and potentially change the contrast coding

1	get_model_matrix(model, type = c("extract", "remake"), contrasts = "restore")

`model`	an `lm` or `lmerMod` model object.
`type`	extract or remake model matrix?
`contrasts`	contrasts settings. These may be restored to those in the model or they may be changed. If a length one character vector (e.g. `"contr.SAS"`) this is applied to all factors in the model, but it can also be a list naming factors for which the contrasts should be set as specified.