expand_nullable{T}(value::Nullable{T}, default::T) :: T

Returns value if it is not null - otherwise default.

file_name_without_extension(file_name, extension = ".jl") :: String

Removes the file extension extension from file_name.

function walk_dir(dir, paths = String[]; only_extensions = ["jl"], only_files = true, only_dirs = false) :: Vector{String}

Recursively walks dir and produces non directories. If only_files, directories will be skipped. If only_dirs, files will be skipped.