refactor: move imports to top

Author: MilesCranmer

src/Expression.jl

@@ -2,7 +2,7 @@
 module ExpressionModule
 
 using DispatchDoctor: @unstable
-using ChainRulesCore: @ignore_derivatives
+using ChainRulesCore: CRC
 
 using ..NodeModule: AbstractExpressionNode, Node
 using ..OperatorEnumModule: AbstractOperatorEnum, OperatorEnum
@@ -19,7 +19,12 @@ import ..NodeUtilsModule:
     has_constants,
     get_constants,
     set_constants!
+import ..EvaluateModule: eval_tree_array, differentiable_eval_tree_array
+import ..EvaluateDerivativeModule: eval_grad_tree_array
+import ..EvaluationHelpersModule: _grad_evaluator
+import ..StringsModule: string_tree, print_tree
 import ..ChainRulesModule: extract_gradient
+import ..SimplifyModule: combine_operators, simplify_tree!
 
 """A wrapper for a named tuple to avoid piracy."""
 struct Metadata{NT<:NamedTuple}
@@ -280,8 +285,6 @@ function extract_gradient(
     return extract_gradient(gradient.tree, get_tree(ex))
 end
 
-import ..StringsModule: string_tree, print_tree
-
 function string_tree(
     ex::AbstractExpression,
     operators::Union{AbstractOperatorEnum,Nothing}=nothing;
@@ -311,8 +314,6 @@ function Base.show(io::IO, ::MIME"text/plain", ex::AbstractExpression)
     return print(io, string_tree(ex))
 end
 
-import ..EvaluateModule: eval_tree_array, differentiable_eval_tree_array
-
 function max_feature(ex::AbstractExpression)
     return tree_mapreduce(
         leaf -> leaf.constant ? zero(UInt16) : leaf.feature,
@@ -344,8 +345,6 @@ function eval_tree_array(
     return eval_tree_array(get_tree(ex), cX, get_operators(ex, operators); kws...)
 end
 
-import ..EvaluateDerivativeModule: eval_grad_tree_array
-
 # skipped (not used much)
 #  - eval_diff_tree_array
 #  - differentiable_eval_tree_array
@@ -360,8 +359,6 @@ function eval_grad_tree_array(
     return eval_grad_tree_array(get_tree(ex), cX, get_operators(ex, operators); kws...)
 end
 
-import ..EvaluationHelpersModule: _grad_evaluator
-
 function Base.adjoint(ex::AbstractExpression)
     return ((args...; kws...) -> _grad_evaluator(ex, args...; kws...))
 end
@@ -382,6 +379,4 @@ function (ex::AbstractExpression)(
     return get_tree(ex)(X, get_operators(ex, operators); kws...)
 end
 
-import ..SimplifyModule: combine_operators, simplify_tree!
-
 end