Неверная синтаксическая ошибка, но я не могу ее обнаружить? (Питон) ⇐ Python

[Anonymous]

Вот мой код: синтаксическая ошибка находится в строке 18. Я пытаюсь понять, почему я получаю эту ошибку.
from visual import *

def Efield(pos, charge)

"""
Calculate electric field due to point charge

Inputs
======

pos - Position where the E field is required (vector)
charge.pos - Position of the charge (vector)
charge.q - Charge (float)

Returns
=======

The electric field vector
"""

r = vector(charge.pos) - vector(pos) # Vector from pos to chargepos

E = float(q) * r / abs(r)**3 # Coulomb's law

return E

# Create some charges

charge1 = sphere(pos=(0,2,0), q=1, radius=0.2, color=color.red) # Positive charge
charge2 = sphere(pos=(0,-2,0), q=-1, radius=0.2, color=color.blue) # Negative charge

# Generate arrows at random locations
random.seed(1234) # Specify a random seed

n = 500
for i in range(n):
x = random.uniform(-4 4)
y = random.uniform(-4,4)
z = random.uniform(-4,4)

pos = vector(x,y,z)

# Make sure pos is not too close to both positive and negative charge
if abs(pos - charge1.pos) > 1 and abs(pos - charge2.pos) > 1:
# Create an arrow if it's far enough from both charges
a = arrow(pos=pos, axis= Efield(pos, charge1) + Efield(pos,charge1))


Подробнее здесь: https://stackoverflow.com/questions/425 ... -it-python