from typing import List


def numeric_filter_string(filter_string: str, comp_type: int,
                          thresholds: List[int]) -> str:
    """ Generate string for a numeric filter.

    Generates a numeric filter string that will be added to the main
    SQL query.

    Args:
        filter_string: Start of the filter string containing the column
        comp_type: Indicates a [1] ≤ comparison, [2] ≥ comparison, [3] range,
            or [4] missing value filter
        thresholds: List of threshold values for the comparisons
    
    Returns:
        filter_string: The formatted numeric filter string
    """
    if comp_type == 1:
        filter_string += "<= {}".format(thresholds[0])
    elif comp_type == 2:
        filter_string += ">= {}".format(thresholds[0])
    elif comp_type == 3:
        filter_string += f"between {thresholds[0]} and {thresholds[1]}"
    elif comp_type == 4:
        filter_string += "is null"
    return(filter_string)