yoriginal: numeric outcome vector, unprojected if there are fixed effects
Xoriginal: numeric design matrix, unprojected if there are fixed effects. Any column named "(Intercept)" will be dropped
weights: numeric weights vector
cluster: numeric cluster vector
fixed_effects: character matrix of fixed effect groups
ci: boolean that when T returns confidence intervals and p-values
se_type: character denoting which kind of SEs to return
has_int: logical, whether the model has an intercept, used for R2
alpha: numeric denoting the test size for confidence intervals
return_vcov: logical, whether to return the vcov matrix for later usage
return_fit: logical, whether to return fitted values
try_cholesky: logical, whether to try using a cholesky decomposition to solve LS instead of a QR decomposition
iv_stage: list of length two, the first element denotes the stage of 2SLS IV estimation, where 0 is used for OLS. The second element is only used for the second stage of 2SLS and has the first stage design matrix. For OLS, the default, list(0), for the first stage of 2SLS list(1), for second stage of 2SLS list(2, first_stage_design_mat).