Remove duplicate

src/constraints.jl

@@ -19,25 +19,6 @@ implemented if `model` does not support free variables. For instance, if a
 solver requires all variables to be nonnegative, it should implement this
 method and return `false` because free variables cannot be copied to the solver.
 
-Note that free variables are not explicitly set to be free by calling
-[`add_constraint`](@ref) with the set [`Reals`](@ref), instead, free variables
-are created with [`add_variable`](@ref) and [`add_variables`](@ref).
-If `model` does not support free variables, it should not implement
-[`add_variable`](@ref) nor [`add_variables`](@ref) but should implement
-this method and return `false`. This allows free variables to be bridged as the
-sum of a nonnegative and a nonpositive variables.
-""" # Implemented as only one method to avoid ambiguity
-function supports_constraint(model::ModelLike, F::Type{<:AbstractFunction},
-                             S::Type{<:AbstractSet})
-    return F == VectorOfVariables && S == Reals
-end
-
-    supports_constraint(model::ModelLike, ::Type{VectorOfVariables}, ::Type{Reals})::Bool
-
-Return a `Bool` indicating whether `model` supports free variables.
-By default, this method returns `true` so it should only be implemented if
-`model` does not support free variables.
-
 Note that free variables are not explicitly set to be free by calling
 [`add_constraint`](@ref) with the set [`Reals`](@ref), instead, free variables
 are created with [`add_variable`](@ref) and [`add_variables`](@ref).