fx.get_axes_val_names: Extract the column names that correspond to the X and Y axis
In evanbiederstedt/sandbox: The functions

Very simple function that's basically just an error check for whether the regex we think should be extracting the names of columns corresponding to X and Y values work as expected: there should only be two values returned.

1	fx.get_axes_val_names(in.df, X = "x_axs", Y = "y_axs")

`in.df`	Data.frame whose names() will be used to extract the instance that matches `X` and `Y`
`X`	name or integer index of the column that will be used for X axis values. The default is "x_axs".
`Y`	name or integer index of the column that will be used for Y axis values. The default is "y_axs".