Vim Colour Scheme Automatic Look-up

This is a sort-of follow-up to my last post. It might help if you're reading this to take a look at my rant about vim colours. I've added this function to my ~/.vim/plugin/ folder: everything in the plugin folder is loaded into vim at startup.

" FILE: ~/.vim/plugin/myColour.vim
function MyColour()
    " My preferred colours for various file types (":set filetype" to find the filetype)
    " ( "Dictionaries")
    let myColours = {
                \   'html'      : 'nightsky',
                \   'javascript': 'nightsky',
                \   'python'    : 'tir_black',
                \   'rst'       : 'nightsky',
                \   'sh'        : 'tir_black',
                \   'vim'       : 'shobogenzo',
                \   'yaml'      : 'badwolf',
                \   }
    if has_key(myColours, &filetype)
        let newcolour = get(myColours, &filetype)
        execute "colorscheme " . newcolour
        echom "No colour scheme found for this filetype"

I've also edited most of the files in ~/.vim/ftplugin/ to terminate with this:

" set my preferred colour scheme if this is the only buffer:
call IsSingleBuffer("call MyColour()")

See my last post for an explanation of IsSingleBuffer().

And I added a line to my ~/.vimrc file:

let mapleader = "-"
nnoremap <leader>c :call MyColour()<cr>

So typing "-c" in Normal mode will immediately switch the buffer (actually all buffers, vim colours are a PITA that way) to the preferred colour scheme for the current file type.