```
julia> methods(filter)
# 8 methods for generic function "filter":
filter(f, a::Array{T,1} where T) in Base at array.jl:1841
filter(f, Bs::BitArray) in Base at bitarray.jl:1911
filter(f, As::AbstractArray) in Base at array.jl:1819
filter(f, d::Associative) in Base at associative.jl:312
filter(f, s::Set) in Base at set.jl:229
filter(f, s::AbstractString) in Base at strings/basic.jl:462
filter(p, x::Nullable{T}) where T in Base at nullable.jl:257
filter(flt, itr) in Base at deprecated.jl:56
julia> methods(filt)
# 2 methods for generic function "filt":
filt(b::Union{AbstractArray{T,1} where T, Number}, a::Union{AbstractArray{T,1} where T, Number}, x::AbstractArray{T,N} where N) where T in Base.DSP at dsp.jl:19
filt(b::Union{AbstractArray{T,1} where T, Number}, a::Union{AbstractArray{T,1} where T, Number}, x::AbstractArray{T,N} where N, si::AbstractArray{S,N} where N) where {T, S} in Base.DSP at dsp.jl:19
julia>
```

Is there any particular reason why these two functions are not one?