refactor: Remove double empty lines

HepLean/FeynmanDiagrams/Momentum.lean

@@ -26,7 +26,6 @@ vector space.
 This section is non-computable as we depend on the norm on `F.HalfEdgeMomenta`.
 -/
 
-
 namespace FeynmanDiagram
 
 open CategoryTheory
@@ -78,7 +77,6 @@ def euclidInner : F.HalfEdgeMomenta →ₗ[ℝ] F.HalfEdgeMomenta →ₗ[ℝ]
     simp only [euclidInnerAux_symm, LinearMapClass.map_smul, smul_eq_mul, RingHom.id_apply,
       LinearMap.smul_apply]
 
-
 /-- The type which assocaites to each ege a `1`-dimensional vector space.
  Corresponding to that spanned by its total outflowing momentum.  -/
 def EdgeMomenta : Type := F.𝓔 → ℝ
@@ -87,7 +85,6 @@ instance : AddCommGroup F.EdgeMomenta := Pi.addCommGroup
 
 instance : Module ℝ F.EdgeMomenta := Pi.module _ _ _
 
-
 /-- The type which assocaites to each ege a `1`-dimensional vector space.
  Corresponding to that spanned by its total inflowing momentum.  -/
 def VertexMomenta : Type := F.𝓥 → ℝ
@@ -119,7 +116,6 @@ instance : AddCommGroup F.EdgeVertexMomenta := DirectSum.instAddCommGroup _
 
 instance : Module ℝ F.EdgeVertexMomenta := DirectSum.instModule
 
-
 /-!
 
 ## Linear maps between the vector spaces.
@@ -199,7 +195,6 @@ for specific Feynman diagrams.
 
 - Complete this section.
 
-
 -/
 
 /-!
@@ -210,7 +205,6 @@ for specific Feynman diagrams.
 
 - Complete this section.
 
-
 -/
 
 end FeynmanDiagram