/**
 * Masks a string by replacing characters with a mask character, keeping only the last visible characters.
 *
 * @param input - The string to mask
 * @param visible - The number of characters to keep visible at the end (default: 4)
 * @param maskChar - The character used for masking (default: '*')
 * @returns The masked string with the last 'visible' characters shown and the rest replaced with maskChar
 *
 * @example
 * mask("1234567890") // returns "******7890"
 * mask("1234567890", 6) // returns "****567890"
 * mask("password", 2, '#') // returns "######rd"
 * mask("abc", 4) // returns "***" (if input is shorter than visible, all chars are masked)
 *
 * @note Commonly used for masking sensitive information like credit card numbers, phone numbers, and passwords
 */
export declare function mask(input: string, visible?: number, maskChar?: string): string;
/**
 * Redacts portions of a string that match the provided patterns.
 *
 * @param input - The string to redact
 * @param patterns - An array of regular expressions to match against the input string
 * @returns The string with matched patterns replaced with '[REDACTED]'
 *
 * @example
 * redact("Email: john@example.com", [/@\w+\.\w+/]) // returns "Email: john[REDACTED]"
 * redact("Phone: 123-456-7890", [/\d{3}-\d{3}-\d{4}/]) // returns "Phone: [REDACTED]"
 * redact("Name: Alice, ID: 12345", [/\d+/, /[A-Z][a-z]+/]) // returns "Name: [REDACTED], ID: [REDACTED]"
 *
 * @note All matches are replaced sequentially; patterns are applied in order
 */
export declare function redact(input: string, patterns: RegExp[]): string;
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