A horrendous hack is employed in order to do arbitrary likelihood ratio tests: the model matrix is built, the names possibly mangled, then fed in as a symbolic formula to glmer/lmer. This is necessary because there is no (easy) way to specify an arbitrary fixedeffect model matrix in glmer.
1 2 3 4 5 6 7 8 9 10 11 
object 

formula. 

design 
something coercible to a 
... 
In the case of 
which 

singular 

see the section "Methods (by generic)"
update
: update the formula or design matrix
vcov
: return the variance/covariance of component which
coef
: return the coefficients. The horrendous hack is attempted to be undone.
logLik
: return the loglikelihood
pseudoMM
part of this horrendous hack.
strictConvergence
logical
return results even when the optimizer or *lmer complains about convergence
optimMsg
character
record warnings from lme. NA_character_
means no warnings.
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