If want to look up a method is julia, say I am interested in the
implementation of the `sine` function, I just run
```julia
julia> methods(sin)
# 11 methods for generic function "sin":
sin(a::Complex{Float16}) at float16.jl:151
sin(z::Complex{T<:Real}) at complex.jl:548
sin(x::Float64) at math.jl:137
sin(x::Float32) at math.jl:138
sin(a::Float16) at float16.jl:150
sin(x::BigFloat) at mpfr.jl:610
sin(x::Real) at math.jl:139
sin{Tv,Ti}(A::SparseMatrixCSC{Tv,Ti}) at sparse/sparsematrix.jl:648
sin{T<:Number}(::AbstractArray{T<:Number,1}) at operators.jl:380
sin{T<:Number}(::AbstractArray{T<:Number,2}) at operators.jl:381
sin{T<:Number}(::AbstractArray{T<:Number,N}) at operators.jl:383
```
But it seems that there is no clear way of locating the sources files of
macros. Or is there?
