---
title: "Start from a working program: cheat sheet"
subtitle: "Python functions and events"
---

# Start from a working program

> The commands and patterns from this unit. In the tutorial, open **Reference** in any playground to copy them.

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**forward**: Move the turtle forward. The number is how many steps.

```python
forward(100)
```

:::

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**backward**: Move the turtle backward without turning.

```python
backward(100)
```

:::

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**right**: Turn clockwise by this many degrees.

```python
right(90)
```

:::

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**left**: Turn anticlockwise by this many degrees.

```python
left(90)
```

:::

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**goto**: Jump to a position. (0, 0) is the centre; x goes right, y goes up.

```python
goto(0, 0)
```

:::

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**penup**: Lift the pen so moving does not draw.

```python
penup()
```

:::

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**pendown**: Put the pen down so moving draws again.

```python
pendown()
```

:::

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**pensize**: Set how thick the line is.

```python
pensize(5)
```

:::

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**pencolor**: Set the line colour, using a colour name.

```python
pencolor("red")
```

:::

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**fillcolor**: Choose the colour to fill shapes with.

```python
fillcolor("blue")
```

:::

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**begin_fill / end_fill**: Everything drawn between these two lines is filled in.

```python
begin_fill()

end_fill()
```

:::

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**speed**: How fast the turtle moves, from 1 (slow) to 10 (fast).

```python
speed(10)
```

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**circle**: Draw a circle with this radius.

```python
circle(50)
```

:::

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**square (loop)**: Draw a square by repeating forward and right four times.

```python
for i in range(4):
    forward(100)
    right(90)
```

:::

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**for loop**: Repeat the indented lines this many times.

```python
for i in range(4):
    pass
```

:::

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**if / else**: Do one thing or the other, depending on a condition.

```python
if x > 0:
    pass
else:
    pass
```

:::

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**every other**: i % 2 == 0 is true on every second pass.

```python
for i in range(8):
    if i % 2 == 0:
        pass
    else:
        pass
```

:::

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**variable**: Give a value a name, so you can reuse and change it.

```python
size = 50
```

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**counter step**: Use the counter i to make each pass different.

```python
for i in range(20):
    forward(i * 5)
    right(90)
```

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**grow value**: Change a value every pass: read the old one, store a new one.

```python
size = 5
for i in range(20):
    forward(size)
    right(90)
    size = size + 5
```

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**list**: Keep many values in order under one name. The first item is place 0.

```python
colours = ["red", "blue", "green"]
```

:::