store the actual source code of a method

Julia has a lot of useful REPL things like methods and help. However, I still end up needing to just look at the code to see what it's doing. It would be cool to be able to do:

julia> methods(base)
# methods for generic function base
base(base::Integer,n::Integer,pad::Integer) at intfuncs.jl:290
base(symbols::Array{Uint8,N},n::Integer,p::Integer) at intfuncs.jl:291
base(base_or_symbols::Union(Integer,Array{Uint8,N}),n::Integer) at intfuncs.jl:292

julia> implementation(base,1)
base(base::Integer, n::Integer, pad::Integer) = _base(dig_syms,int(base),unsigned(abs(n)),pad,n<0)

julia> implementation(base,3)
base(base_or_symbols::Union(Integer,Array{Uint8}), n::Integer) = base(base_or_symbols, n, 1)

It's kind of like the jump-to code stuff in some IDEs, but in the REPL, and only showing the one function. This obviously has limitations, since you can't just scroll up and see the implementation of _base or search for the definition of dig_syms in that file, but it does let you see what the default values are.

You can already see the signature for _base, which makes the implementations of base more meaningful. (without needing to switch from the REPL to a text editor)

julia> methods(Base._base)
# methods for generic function _base
_base(symbols::Array{Uint8,N},b::Int32,x::Unsigned,pad::Int32,neg::Bool) at intfuncs.jl:278

Considering that the line numbers/files are already included in the output of methods, it seems like it should be straightforward to grab the appropriate lines of code from the file.