Parse formulas objects for use in brms.

```
brmsterms(formula, ...)
# S3 method for default
brmsterms(formula, ...)
# S3 method for brmsformula
brmsterms(formula, check_response = TRUE, resp_rhs_all = TRUE, ...)
# S3 method for mvbrmsformula
brmsterms(formula, ...)
```

## Arguments

- formula
An object of class `formula`

,
`brmsformula`

, or `mvbrmsformula`

(or one that can
be coerced to that classes): A symbolic description of the model to be
fitted. The details of model specification are explained in
`brmsformula`

.

- ...
Further arguments passed to or from other methods.

- check_response
Logical; Indicates whether the left-hand side
of `formula`

(i.e. response variables and addition arguments)
should be parsed. If `FALSE`

, `formula`

may also be one-sided.

- resp_rhs_all
Logical; Indicates whether to also include response
variables on the right-hand side of formula `.$allvars`

,
where `.`

represents the output of `brmsterms`

.

## Value

An object of class `brmsterms`

or `mvbrmsterms`

(for multivariate models), which is a `list`

containing all
required information initially stored in `formula`

in an easier to use format, basically a list of formulas
(not an abstract syntax tree).

## Details

This is the main formula parsing function of brms.
It should usually not be called directly, but is exported to allow
package developers making use of the formula syntax implemented
in brms. As long as no other packages depend on this functions,
it may be changed without deprecation warnings, when new features make
this necessary.