How to create a function based on these process

I have multiple Mplus CFA model outputs (cfa.out) from MplusAutomation. I want to create a R function based on these procedure. Can anyone guide me how to write a function in R? All the process will be the same except the output file (cfa.out here). I tried several different ways, but it didn't work well.

library(MplusAutomation)
library(dplyr)
library(stringr)
library(tidyr)

dat <-readModels("cfa.out", what = "parameters")$parameters
dat2 <- filter(as.data.frame(dat$unstandardized), grepl("BY", paramHeader))

#loadings 
loading <- dat2 %>% 
filter(grepl("BY", paramHeader)) %>% 
select(c(param, est)) %>% 
separate(param, c("loading","time")) %>%
mutate(time = paste0('time',time)) %>% 
spread(loading, est)

Let's assume my dat2 is this;

paramHeader <- c('F1_3.BY','F1_3.BY','F1_3.BY','F1_15.BY','F1_15.BY', 'F1_15.BY',
             'F1_25.BY','F1_25.BY','F1_25.BY','F1_35.BY','F1_35.BY','F1_35.BY',
             'F1_47.BY','F1_47.BY','F1_47.BY','F1_57.BY','F1_57.BY','F1_57.BY',
             'Intercepts','Intercepts','Intercepts','Intercepts','Intercepts',
             'Intercepts','Intercepts','Intercepts','Intercepts','Intercepts',
             'Intercepts','Intercepts','Intercepts','Intercepts','Intercepts',
             'Intercepts','Intercepts','Intercepts')
param    <- c('V1_3','V2_3','V3_3','V1_15','V2_15', 'V3_15',
          'V1_25','V2_25','V3_25','V1_35','V2_35','V3_35',
          'V1_47','V2_47','V3_47','V1_57','V2_57','V3_57',
          'V1_3','V2_3','V3_3','V1_15','V2_15', 'V3_15',
          'V1_25','V2_25','V3_25','V1_35','V2_35','V3_35',
          'V1_47','V2_47','V3_47','V1_57','V2_57','V3_57')
est      <- c(1,1.122,.917,1,1.069,.867,1,1.066,.917,1,1.048,.994,1,1.03,.937,1,1.133,1.032,
          1,1.122,.917,1,1.069,.867,1,1.066,.917,1,1.048,.994,1,1.03,.937,1,1.133,1.032)
se       <- c(0,.044,.045,0,.036,.039,0,.034,.037,0,.034,.037,0,.031,.034,0,036,.037,
          0,.044,.045,0,.036,.039,0,.034,.037,0,.034,.037,0,.031,.034,0,036,.037)
est_se   <-     c(999,25.466,20.385,999,29.751,22.478,999,31.134,24.565,999,31.18,26.587,999,33.637,27.405,999,31.883,28.081,999,25.466,20.385,999,29.751,22.478,999,31.134,24.565,999,31.18,26.587,999,33.637,27.405,999,31.883,28.081)
pval     <- c(999,0,0,999,0,0,999,0,0,999,0,0,999,0,0,999,0,0,
          999,0,0,999,0,0,999,0,0,999,0,0,999,0,0,999,0,0)

dat <- data.frame(paramHeader, param,est,se,est_se,pval)
dat$param <- as.character(dat$param)
dat2