return {
  -- lang server installations
  {
    "williamboman/mason.nvim",
    dependencies = {
      {
        "nvimtools/none-ls.nvim",
        config = function()
          require("null-ls").setup({
            sources = {
              -- assembler
              require("null-ls").builtins.formatting.asmfmt,
              -- lua
              require("null-ls").builtins.formatting.stylua,
              -- markdown
              require("null-ls").builtins.formatting.mdformat,
              -- python
              require("null-ls").builtins.formatting.isort,
              require("null-ls").builtins.formatting.yapf,
              -- shell
              require("null-ls").builtins.formatting.shfmt,
              -- yaml
              require("null-ls").builtins.formatting.yamlfmt,
            },
          })
        end,
      },
      {
        "jay-babu/mason-null-ls.nvim",
        opts = {
          automatic_installation = true,
          ensure_installed = {
            -- assembler
            "asmfmt",
            -- lua
            "stylua",
            -- markdown
            "mdformat",
            -- python
            "isort",
            "yapf",
            -- shell
            "shfmt",
            -- yaml
            "yamlfmt",
          },
        },
      },
    },
    opts = { ui = { icons = Install_signs } },
  },
}