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![Sai C](https://secure.gravatar.com/avatar/6563ad826ffb8690463eb26f497e81ee?s=96&d=https%3A%2F%2Fecs-static.teamtreehouse.com%2Fassets%2Fcontent%2Fdefault_avatar-445fbbabfc8dc9188fb5967fe43322ee0c3e0dd1e10f378bf8343784af5a13eb.webp&r=pg)
Sai C
2,577 PointsI don't understand taco_joints = restaurants.copy()
so the definition part says taco_joints = restaurants.copy() ← but restaurants is not defined? how did python make a copy of it? if we are making a copy of all_restaurants, shouldn't it be all_restaurants.copy()?
and if taco_joints is already a copy of all_restaurants, why are we still making a copy of it? to me it seems we have the original data in all_restaurant, and can modify in taco_joints, which is a copy of the former list
1 Answer
![Steven Parker](https://uploads.teamtreehouse.com/production/profile-photos/969492/micro_tool_chess_set_2.jpg)
Steven Parker
230,688 PointsThe definition of "restaurants" is on the line above the assignment:
def tacos_only(restaurants): # restaurants is defined here as the parameter
taco_joints = restaurants.copy()
So, when the function is called with "all_restaurants" as the argument, the parameter name "restaurants" becomes a reference to "all_restaurants" (but not a copy). So this copy is made in "taco_joints" so it can be altered without affecting the original.
Then for the loop, "taco_joints" is also copied so altering it won't disturb the loop iterations.
Sai C
2,577 PointsSai C
2,577 PointsThank you! understood