
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given the parabola $C$: $x^{2}=4y$ with focus $F$ and the directrix intersecting the $y$-axis at point $Q$. A line $l$ passing through point $Q$ intersects the parabola $C$ at two distinct points $A$ and $B$.  
$(1)$ If $|AB|=4 \sqrt {15}$, find the equation of line $l$;  
$(2)$ If point $F$ is outside the circle with diameter $AB$, find the range of values for the slope of line $l$.

Present the answer in LaTex format: \boxed{Your answer}
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