
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 complex number $z = (k^2 - 3k - 4) + (k - 1)i$ ($k \in \mathbb{R}$):

$(1)$ If the point corresponding to the complex number $z$ is located in the second quadrant on the complex plane, find the range of values for $k$;

$(2)$ If the complex number $z \cdot i \in \mathbb{R}$, find the modulus of the complex number $z$, $|z|$.

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