sts_plot = new.env()

sts_plot$legend = function( legend , … ){

if( (! is.character(legend)) ){
  stop("legend argument requires character vector")
}

args = list(...)
args$legend = legend
args$x = if_exist_else ( "x", args, paste( "topleft" ))

do.call( get_pkg_fun( "graphics::legend") , args )

}

sts_plot$hist = function( data , var , … ){

if( (! is.character(var)) || length(var) != 1 ){
  stop("vars argument requires character vector with size of 1")
}

args = list(...)
args$x = data[[var]]
args$main = if_exist_else ( "main", args, paste( "Frequency of" , var ))
args$xlab = if_exist_else ( "xlab", args, paste( var ))

do.call( get_pkg_fun( "graphics::hist") , args )

}

sts_plot$box = function( data , var , … ){

if( (! is.character(var)) || length(var) != 1 ){
  stop("vars argument requires character vector with size of 1")
}

args = list(...)
args$x = data[[var]]
args$main = if_exist_else ( "main", args, paste( var ))
args$lex.order = TRUE

do.call( get_pkg_fun( "graphics::boxplot"), args )

}

sts_plot$scatter = function( data , vars , … ){

if( (! is.character(vars)) || length(vars) != 2 ){
  stop("vars argument requires character vector with size of 2")
}

args = list(...)
args$x = data[vars]
args$main = if_exist_else ( "main", args, paste( vars[1], "vs", vars[2] ))

do.call( get_pkg_fun( "graphics::plot"), args )

}