Getting Error cs0103

heres my code pls help btw the error is on lines with Handles.DrawLine like line 64:

using UnityEditor;
using UnityEngine;

public static class PlainMath {
const float size = 0.25f;

public static void NextGizmosColor () {
Gizmos.color = Color.HSVToRGB (Random.value, 1, 1);
}

public static float AngleFromDirection (Vector2 dir) {
//Get the angle by using some Acos on x, flipping the rotation when y is lower then 0.
dir = dir.normalized;
var angle = Mathf.Acos (dir.x) * Mathf.Rad2Deg;
return dir.y > 0 ? angle : 360 - angle;
}

public static float AngleBetween (Vector2 A, Vector2 B) {
A -= B;
float angle = Mathf.Atan2 (A.y, A.x);
return angle * Mathf.Rad2Deg;
}

public static Vector2 ClosestOnLine (Vector2 origin, Vector2 direction, Vector2 point) {
direction.Normalize ();
Vector2 lhs = point - origin;

Gizmos.color = Color.black;

float dotP = Vector2.Dot (lhs, direction);
return origin + direction * dotP;
}
public static Vector3 CalculateClosestToRinPlaneABwD (Vector3 A, Vector3 B, Vector3 respectPoint, Vector3 targetPoint) {
// this method, will return the closest point on the plane, to the respect point
// while it will give as a point, that has the same langth, as respectPoint, from the center of the plain

// create a plain, while the Z axis is the B-A vector,
// move the plain so respectPoint, is a point on the plane.
Plane plane = new Plane (B - A, respectPoint);
// get the center of the plane, A.k.a, the point at witch respectPoint is closest to the RespectPoint (in world space).
// a.k.a 90 degree angle between respect point and the Line AB (infinite line)
Vector3 center = plane.ClosestPointOnPlane (A);
// get the closest point on plane to target
Vector3 closest = plane.ClosestPointOnPlane (targetPoint);
// find the closest point, to target.
// this point has the same distance to A, and to B from respectPoint, and yet the closest one to targetPoint
Vector3 dir = (closest - center).normalized;
dir *= (respectPoint - center).magnitude;

return dir + center;
}
public static Vector3 GetClosestWithRespectVisualized (Vector3 A, Vector3 B, Vector3 R, Vector3 Target) {
Gizmos.color = Color.blue;
Gizmos.DrawSphere (A, size);
Gizmos.DrawSphere (B, size);
Gizmos.color = Color.green;
Gizmos.DrawSphere (R, size);
Gizmos.color = Color.red;
Gizmos.DrawSphere (Target, size);

Plane plane = new Plane (A - B, R);
Vector3 center = plane.ClosestPointOnPlane (A);

Handles.DrawLine (B, A);

Random.InitState (10);
NextGizmosColor ();
Gizmos.DrawSphere (center, size);

return Vector3.zero;
}
public static Vector3 GetClosestWithRespectVisualized (Vector3 A, Vector3 B, Vector3 respectPoint, Vector3 targetPoint, Vector3 Zero) {
// this method, will return the closest point on the plane, to the respect point
// while it will give as a point, that has the same langth, as respectPoint, from the center of the plain

// create a plain, while the Z axis is the B-A vector,
// move the plain so respectPoint, is a point on the plane.
Plane plane = new Plane (B - A, respectPoint);
// get the center of the plane, A.k.a, the point at witch respectPoint is closest to the RespectPoint (in world space).
// a.k.a 90 degree angle between respect point and the Line AB (infinite line)
Vector3 center = plane.ClosestPointOnPlane (A);

Gizmos.color = Color.black;
Gizmos.DrawSphere (Zero + center, 0.3f);
Handles.DrawLine (B + Zero, A + Zero);
Handles.DrawLine (center + Zero, respectPoint + Zero);
// get the closest point on plane to target
Vector3 closest = plane.ClosestPointOnPlane (targetPoint);

Gizmos.color = Color.grey;
Gizmos.DrawSphere (closest + Zero, 0.1f);
Handles.DrawLine (closest + Zero, targetPoint + Zero);
Handles.DrawLine (closest + Zero, center + Zero);

// find the closest point, to target.
// this point has the same distance to A, and to B from respectPoint, and yet the closest one to targetPoint
Vector3 dir = (closest - center).normalized;
dir *= (respectPoint - center).magnitude;

Gizmos.color = Color.yellow;
Gizmos.DrawSphere (dir + Zero + center, 0.1f);
Handles.DrawLine (dir + Zero + center, center + Zero);
Handles.DrawLine (dir + Zero + center, respectPoint + Zero);

return dir + center;
}
}

Please use code tags ( Using code tags properly ) and please include the full text of the error including the error description and the line number (which is part of the error message in parentheses).