The terraform state file is locked when a Terraform operation that could write state is in progress. This prevents concurrent state operations that could corrupt the state. The forbidden actions when the state file is locked are those that could write state, such as terraform apply, terraform destroy, terraform refresh, terraform taint, terraform untaint, terraform import, and terraform state *. The terraform validate command is also forbidden, because it requires an initialized working directory with the state file. The allowed actions when the state file is locked are those that only read state, such as terraform plan, terraform show, terraform output, and terraform console. References = [State Locking] and [Command: validate]

This is how Terraform determines dependencies between resources, by using the references between them in the configuration files and other factors that affect the order of operations.

The terraform import command is used to import existing infrastructure into your Terraform state. This command takes the existing resource and associates it with a resource defined in your Terraform configuration, updating the state file accordingly. It does not generate configuration for the resource, only the state.

In Terraform, the max function can be used to select the largest number from a list of numbers. The max function takes multiple arguments and returns the highest one. For the list numcpus = [18, 3, 7, 11, 2], using max(numcpus...) will return 18, which is the largest number in the list.
References:
Terraform documentation on max function: Terraform Functions - max

This is not a responsibility of a Terraform provider, as it does not make sense grammatically or logically. A Terraform provider is responsible for exposing resources and data sources based on an API, managing actions to take based on resource differences, and understanding API interactions with some service.