name.pieces: Name the elements that go into your regression function.
In jackiemauro/hurdleIV:

There is likely a cleaner way to do this, but it allows for more flexibility as to how many of each parameter you're going to have.

1 2	name.pieces(t, a1 = len_cov, a2 = num_betas, a3 = num_endog, a4 = numpis)

`t`	a vector which should start with the covariates, then the betas, then the gammas, then the pis
`a1`	the number of elements in the covariance matrix
`a2`	the number beta coefficients (2nd stage linear regression)
`a3`	the number endogenous regressors
`a4`	a list of the number of pi coefficients (1st stage regression) for each endogenous regressor