Rates are represented as strings that consist of an integer value followed by the symbol
/ and a duration. The duration specifies the time interval over which the integer value is to be distributed. For example:
rate1 = "20 / 5m" # 20 every 5 minutes
rate2 = "1 / 1d" # 1 per day
In the first example,
20 / 5m represents a rate of 20 occurrences per 5 minutes. In the second example,
1 / 1d represents a rate of 1 occurrence per day. The integer value, the
/ symbol, and the duration must be enclosed in quotes or string literals in order to be treated as a string in the TOML file.